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Storage Access Network Scenario
Figure 9-4 illustrates a stack of three PowerConnect 6200 Series switches connecting two servers (iSCSI
initiators) to a disk array (iSCSI targets). There are two iSCSI connections as follows:
Session A: 10.1.1.10 to 10.1.1.3
Session B: 10.1.1.11 to 10.1.1.1
An iSCSI application running on the management unit (the top unit in the diagram) has installed
priority filters to ensure that iSCSI traffic that is part of these two sessions receives priority treatment
when forwarded in hardware.
Figure 9-4. NSF and a Storage Area Network
When the management unit fails, session A drops. The initiator at 10.1.1.10 detects a link down on its
primary NIC and attempts to reestablish the session on its backup NIC to a different IP address on the
disk array. The hardware forwards the packets to establish this new session, but assuming the session is
established before the control plane is restarted on the backup unit, the new session receives no priority
treatment in the hardware.
Session B remains established and fully functional throughout the restart and continues to receive
priority treatment in the hardware.
Servers (iSCSI Initiators)
10.1.1.10
10.1.1.11
10.1.1.3
10.1.1.2
10.1.1.1
Disc Array (iSCSI Targets)